Field of the Invention
The invention is in the field of medical technology and is directed to a method and a device for repairing a human or animal joint, in particular a small synovial joint such as a human facet joint, a joint of the human hand or foot (including finger and toe joints), a sacroiliac joint, sternoclavicular joint, sternocostal articulation or a costovertebral joint, but also cartilaginous joints, in particular intervertebral joints. The expression “repairing a joint” is used herein in the sense of surgery concerning both articular surfaces of the joint by introducing a device in the joint and fastening it to both articular surfaces, wherein after the surgery, the joint will be capable of at least restricted articulation, i.e. the repair is not a so called joint fusion (no articulation capability after surgery) but it is e.g. a joint resurfacing (approximately full articulation capability maintained or restored).
Description of Related Art
The publication U.S. Pat. No. 5,571,191 (Fitz) discloses methods and devices for resurfacing human facet joints, wherein the device comprises two independent cap-like components to be fastened to the articular processes of the joint in two successive surgical steps, each one of the components constituting an artificial articular surface. WO 2008/034276 also discloses a method and a device for such resurfacing. For the surgery as proposed in both named cases, it is necessary to make the articular surfaces of the joint to be treated accessible either by dislocating or luxating the joint or by largely resecting the joint capsule and the related ligaments.
The publication US-2009/171394 (Abdou) discloses methods and devices for surgically treating human facet joints by providing in each one of the articular surfaces un undercut groove, the grooves being located opposite one another, and by introducing through a cannula a device into the grooves, wherein cannula and device have cross sections adapted to the pair of opposite undercut grooves. The device is initially retained in the grooves by a press fit, followed by osseointegration. The device comprises two device parts, of which one fits into each one of the pair of opposite undercut grooves. The device parts are separate from each other or they are connected to each other either rigidly or through an elastomeric portion. Depending on the choice of the type of device, after such surgery, the treated joint will allow full articulation (separate device parts), limited articulation (elastomeric connection between the device parts) or no articulation (rigidly connected device parts), i.e. joint fusion.
The publication WO2010/045749 (WW Technology), which is enclosed herein in its entirety by reference, describes devices and methods for fusing a small synovial joint in a human or animal patient, in particular a human facet joint, by introducing between the suitably prepared articular surfaces of the joint a fusion device and by anchoring the fusion device in both articular surfaces by in situ liquefaction of a material having thermoplastic properties and being suitably arranged on the fusion device, and by letting the liquefied material penetrate into bone tissue of the articular surfaces, where on re-solidification it constitutes a positive fit connection between the fusion device and the bone tissue. For the in situ liquefaction, application of vibrational energy (in particular ultrasonic vibration) to the fusion device is preferred and for restricting the liquefaction to desired locations and therewith preventing undue thermal load in tissue near the surgical site, thermoplastic materials (and preferably other materials comprised by the device) are chosen to be capable of vibration energy transmission with little loss (no inner liquefaction) such limiting liquefaction to interfaces between a vibrating element (device or device part) and a counter element (bone tissue or further device part), which interfaces are situated at locations where liquefaction and penetration is desired.